Orgo Final Distillation Exam Questions With Complete
Solutions
A part of the microscale kit that was used in the simple and
fractional distillation apparatus set up is shown below (see item
(c) on pg. 15) What is the function of this part in the apparatus?
Correct Answers (Pictured: thermometer adapter) To ensure
that the bulb of the thermometer doesn't touch the side of the
distilling head
A part of the microscale kit was used in the simple and
fractional distillation apparatus set up is shown below (see item
(m) on pg. 15) What source o error is introduced if the connector
part of the piece above is loose? Correct Answers (pictured is
connector with support rod) vapors could escape, thus losing
liquid
A piece of glassware from the microscale kit that was used in
the fractional distillation apparatus set up is shown below (see
item (o) on pg. 15). Correct Answers distillation column/air
condenser
A piece of glassware from the microscale kit that was used in
the simple and fractional distillation apparatus set up is shown
below (see item (h) on pg. 15). Correct Answers claisen
adapter/distillation head w/ air condenser
Behavior of temperature during a simple or fractional distillation
of a mixture Correct Answers temp increases
, Besides removing water chemically from 95% ethanol, what is
another method of forming 100% ethanol? Correct Answers
removing water as an azeotrope with another liquid
Boiling point composition graph - fig. 5.3 and 5.4 Correct
Answers phases in the graph and how to interpret data from the
graph (liquid and vapor composition of mixture - see graph and
explanation pg. 91 and 92)
Both steam and vacuum distillations allow liquids to boil below
the actual boiling points. What differentiates these two types of
distillations? Correct Answers steam is for immiscible mixtures
and vacuum is for miscible mixtures
Calculate the mole fraction of B (XB) in the vapor if a mixture
of liquids is 65% A and 35% B. The vapor pressure of pure A is
800 torr and the vapor pressure of pure B is 900 torr. Show
calculations and give answer to 2 decimal places. Correct
Answers Xb=Pb/Ptotal Xb= 315/835 = .377
Pa=paNa 520 torr = (800)(.65)
Pb=PbNb 315 torr = (900) (.35)
520 + 315 = Ptotal=835 torr
Definition of azeotrope (minimum and max) - recognize
azeotrope on bp composition graph Correct Answers -Def: mix
with a fixed composition that cannot be altered by simple or
fractional distillation, has constant boiling point.
-Min: bp is below that of the pure boiling of the pure mixtures
-Max: bp is above that of the pure solutions boiling points
Solutions
A part of the microscale kit that was used in the simple and
fractional distillation apparatus set up is shown below (see item
(c) on pg. 15) What is the function of this part in the apparatus?
Correct Answers (Pictured: thermometer adapter) To ensure
that the bulb of the thermometer doesn't touch the side of the
distilling head
A part of the microscale kit was used in the simple and
fractional distillation apparatus set up is shown below (see item
(m) on pg. 15) What source o error is introduced if the connector
part of the piece above is loose? Correct Answers (pictured is
connector with support rod) vapors could escape, thus losing
liquid
A piece of glassware from the microscale kit that was used in
the fractional distillation apparatus set up is shown below (see
item (o) on pg. 15). Correct Answers distillation column/air
condenser
A piece of glassware from the microscale kit that was used in
the simple and fractional distillation apparatus set up is shown
below (see item (h) on pg. 15). Correct Answers claisen
adapter/distillation head w/ air condenser
Behavior of temperature during a simple or fractional distillation
of a mixture Correct Answers temp increases
, Besides removing water chemically from 95% ethanol, what is
another method of forming 100% ethanol? Correct Answers
removing water as an azeotrope with another liquid
Boiling point composition graph - fig. 5.3 and 5.4 Correct
Answers phases in the graph and how to interpret data from the
graph (liquid and vapor composition of mixture - see graph and
explanation pg. 91 and 92)
Both steam and vacuum distillations allow liquids to boil below
the actual boiling points. What differentiates these two types of
distillations? Correct Answers steam is for immiscible mixtures
and vacuum is for miscible mixtures
Calculate the mole fraction of B (XB) in the vapor if a mixture
of liquids is 65% A and 35% B. The vapor pressure of pure A is
800 torr and the vapor pressure of pure B is 900 torr. Show
calculations and give answer to 2 decimal places. Correct
Answers Xb=Pb/Ptotal Xb= 315/835 = .377
Pa=paNa 520 torr = (800)(.65)
Pb=PbNb 315 torr = (900) (.35)
520 + 315 = Ptotal=835 torr
Definition of azeotrope (minimum and max) - recognize
azeotrope on bp composition graph Correct Answers -Def: mix
with a fixed composition that cannot be altered by simple or
fractional distillation, has constant boiling point.
-Min: bp is below that of the pure boiling of the pure mixtures
-Max: bp is above that of the pure solutions boiling points
